Decided to install the Vetterman Exhaust tonight. #3 and 4 are connected first then installed on the flanges with 1 ea Gasket Washer, Lock washer and nuit. Then 1 and 2 get installed. It's called a cross over or Cross flow system. The pipes at the rear get hangers up to the sump bolts then another brace goes across the same clamp from exit pipe to pipe. I'll do this later when the cowl is on. These pipes have a swivel joint that allows for changing the pipe angle for different cowls.
